This invention relates to permanent hose fittings of the socket and insert type which are crimped or swaged onto hose having inner and outer layers of rubber-like material and one or more intermediate layers of wire reinforcement.
Both permanent and reusable hose fittings are well known in the art and typically are characterized further as being of the skive or no-skive variety referring to whether the outer cover of the hose is removed or not to achieve a desired engagement between the inner surface of the socket and the reinforcement or outer cover material. It is the usual practice with relatively high pressure rubber hose to assure that a direct engagement is made between the socket and wire reinforcement so that a secure grip is made upon the hose. This can be done either by the prior step of skiving the hose to expose the reinforcement or by the use of projections on the interior surface of the socket which penetrate the cover and directly engage the reinforcement.
One example of a permanent hose fitting is shown in U.S. Pat. No. 4,106,526. This typifies one form of prior art device in which the hose is prepared for coupling by skiving of the outer cover.
Another form of prior art is described in U.S. Pat. No. 3,287,033, this being a reusable type fitting in which the socket is threaded over the cover of the hose and the insert later added. This art is significant however in that the hose need not be prepared by skiving, in that threads on the socket are designed to cut through the cover and directly engage the wire reinforcement. In this arrangement the socket threads are relatively strong and are adapted to bite into and deflect the wire reinforcement in a preferred undulating pattern between the socket projections which provides a superior grip by utilizing the sharp edges of the socket thread.
One form of permanent fitting adapted to pierce the cover and engage the reinforcement of the hose is shown in U.S. Pat. No. 4,064,614, wherein pyramidal barbs are employed. These barbs are sharply pointed and have a sturdy base and would tend to move radially into the reinforcement upon crimping or swaging without deflecting either the reinforcement or the barbs.
Another form of permanently attachable fitting is disclosed in U.S. Pat. No. 2,797,111 wherein again, generally radially disposed projections are included in the socket to engage the reinforcement. The projections deform upon crimping or swaging in some embodiments apparently in an uncontrolled manner. Further the projections are in the form of threads which slice into the cover upon initial placement of the fitting.